Major goals are to: (1) compare longitudinal subjects of diverse age for evidence of marital, sexual and social variables that vary in relation to age, (2) determine whether individual differences in sexual functioning may be related to social, physiologic or psychologic characteristics, and to (3) discover whether any aspect of prior marital, sexual or social experience may be associated with entities of disease or longevity. On one visit or another to GRC, each participant in the longitudinal study was asked to contribute an interview concerning his history of marriage and sexual activity. The investigator in making this request outlined study objectives, provided assurance of confidence and emphasized the voluntary nature of such a contribution. Questions were memorized along with whatever response categories were needed for the recording of responses. Chapters of the life history pertaining to residential, military, religious, educational, occupational and parental-home experience were reviewed before introducing questions relating to marital adjustment and sexual conduct. This initial questioning provided a variety of information not otherwise obtained, aided rapport and established certain reference ages against which earlier behavior could be oriented in time. At present, 634 subjects have completed interviews. The refusal rate has been 2.1 percent.